Explicitly passing --disable-tm-clone-registry causes gcc to create a
crtbegin.o with a zero-sized .init_array/.fini_array. This in turn
causes ld to complain.
Make CC_GCC_TM_CLONE_REGISTRY a tristate so if it's not explicitly
enabled we can let ./configure decide.
Fixes#1531
Fixes: 1e21a302 ("gcc: Add CT_CC_GCC_TM_CLONE_REGISTRY config")
Signed-off-by: Chris Packham <judge.packham@gmail.com>